Boost to chances of life on two distant moons

Sen—NASA scientists have been carrying out observations and experiments to help discover whether life might have been able to develop on two faraway moons in the Solar System.

Europa, one of the four Galilean satellites of Jupiter, has been found to have abundant quantities of hydrogen peroxide across its surface.

It is being suggested that this much diluted version of hair bleach might mix with the ocean thought to lie beneath Europa’s surface, in which case it would convert to oxygen and so could be an excellent energy supply for simple life.

Meanwhile, an experiment being carried out in a laboratory to simulate the atmosphere of Saturn’s largest moon Titan, where the European Space Agency’s probe Huygens landed in 2005, also offers positive news to those searching for alien life.

The Titan simulation shows that complex organic chemistry that could eventually lead to the building blocks of life extends lower in the atmosphere than had been thought.

The Europa findings are published in a new paper published in the journal Astrophysical Journal Letters by a team led by Kevin Hand, of NASA’s Jet Propulsion Laboratory (JPL) in California.

His co-author Mike Brown, of the California Institute of Technology in Pasadena, used the Keck II Telescope on Mauna Kea, Hawaii, over four nights in September 2011 to observe Europa in near-infrared light.

Two images of Europa's icy surface taken by NASA's Galileo probe. Credit: NASA/JPL/University of Arizona

The results showed that hydrogen peroxide, first detected on Europa by NASA’s Galileo mission to Jupiter, is most greatly concentrated on the side of Europa that leads its orbit around Jupiter. That concentration drops to almost nothing on the trailing side in its orbit.

Brown, who is most famous for his Kuiper Belt discoveries that helped see Pluto lose its status as a planet, said: “The Galileo measurements gave us tantalizing hints of what might be happening all over the surface of Europa, and we’ve now been able to quantify that with our Keck telescope observations.

“What we still don’t know is how the surface and the ocean mix, which would provide a mechanism for any life to use the peroxide.”

Hand said: “Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulphur, and it needs some form of chemical or light energy to get the business of life done.

“Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement.”

Over on Titan, the experiments carried out by another team at JPL have highlighted another region that could brew up prebiotic chemicals which could allow life to form.

Murthy Gudipati, lead author of a paper in Nature Communications, said: “Scientists previously thought that as we got closer to the surface of Titan, the moon’s atmospheric chemistry was basically inert and dull. Our experiment shows that’s not true.

A view of the surface of Titan from the Huygens probe during its descent in January 2005. Credit: ESA/NASA/JPL/University of Arizona

“The same kind of light that drives biological chemistry on Earth’s surface could also drive chemistry on Titan, even though Titan receives far less light from the sun and is much colder. Titan is not a sleeping giant in the lower atmosphere, but at least half awake in its chemical activity.”

The JPL scientists studied the effects of light on a molecule detected on Titan called dicyanoacetylene. Their findings suggest that compex organic material could coat the chunks of water ice found on the moon’s surface and maybe seep through to a liquid water layer beneath the surface.

Edward Goolish, of NASA’s Astrobiology Institute in California, said: “These results suggest that the volume of Titan’s atmosphere involved in the production of more complex organic chemicals is much larger than previously believed. It makes Titan an even more interesting environment for astrobiological study.”